Composition for oil well cementing



7 Sheets-Sheet l Filed Nov. 3, 1948 Don m O T N E oo. V o N M7 Y 2 o ou w 4B V VQ u o d d N oov S L O a. a n 0m 3 a: u M S O 0 n Oc. I. 3 M ooo.. oon.

. mmf-"Q 7 Sheets-Sheet 2 R. A. SALA'THIEL COMPOSITION FOR OIL WELL CEMENTING Jan. 15, 1952 Filed Nov. 3, 1948 AGEYNY.

(Nonnen-1w) sassod uouaisusnoo mvsnron.

Jan- 15, 1952 R. A. sALATHlEL COMPOSITION FOR OIL WELL CEMENTING 7 Sheet's-Sheet Filed Nov. 3, 1948 (NOLIDIIYIVH) SSSIOJ '-AONZLSISNOO azuoul- INVENTOR.

Jan. 15, 1952v a A. sALATHlr-:L 2,582,459

COMPOSITION FOR OIL WELL CEMENTING Filed Nov. 3, 1948 7 Sheets-Sheet 4 'NI OS 83d 'S81 *H LSNBBLS 3`1ISN31.

@KM/a. Mya BY Jan- 15, 1952 R. A. SALATHIEL 2,582,459

COMPOSITION FOR OIL WELL CEMENTING Filed Nov. 3, 1948 7 Sheets-Sheet 5 CLAY ADDED- PERCENT BY IT- 0F DRY GENENT STIRRINQ TIIEZ HOURS FIG. 5.

l ll mvENToR.

AGENT.

Jan- 15, 1952 R. A. sALA'rHlEl. 2,582,459

COMPOSITION FOR OIL WELL CEMENTING Filed Nov. 3, 1948 7 Sheets-Sheet 6 BARREL lll-TEST A sLow ser einem' (4.soA|.PEn.sAcK swan TENSILE STRENGTHl 4IBLBS.PER SQ-III.

BARREL I-TEST A SLO* SET GEIENT (4.56ALPER' SACK SLURRY) TENSILE STRENGTH' 4I6 LIS-PER SQJN.

Q No.3,No.4. BARREL I-TEST A luwnoven centrar connmme raus. wvoume asnromrs Ano 0.5Lss. cALcluu LleuosuLFourrs Psa sicu or o: uewr.

(lo-en :PER sAcK sLuRRY) TENsILE sTneNerM-zn Las. PER som.

(BULLET a suor 'musnlnsu Vnove suLLeT 4.)

GUN PERFORATING TESTS BAR RELm-TEST A HIGH EARLY STRENGTH CEMENT (6.26AL.PER. SACK SLURRY TENSILE STRENGTH '37B LB$.PER $0.1

4" sun 15/32" auLLET, los-@RMN Pawnen annee FIG. 6.'

mvENTon.

COMPOSITION FOR OIL WELL CEMENTING Filed Nov. 3, 194e 7 sneetssheet 7 BARRELII TEST A BARRELILTEST A man :nu srnzuarn ensmmz aumen. sncxnmwvso cuen coummna ls Las.

swan) noname automne Ano o a La. cALclun TsusIL: srncusru 51a Las. Pn so. In. LIGNDSULFONATPER SNK 0F GEIE"- no en .ren sAcx swan) TENSILE STRENGTH 2li LIS-PER $0. Il

BARREL l TEST B SLO' SET CEMENT (4.5 GAL. PER SAGK SLURRY.)

TENSILE STRENBTH I 4I6 LIS. PER $0. Il.

GUN PERFORATING TESTS s me' sun, |5/32"su|.|.sr, :5-0mm wolven cane:

FIG. 7.l

Patented Jan. l5, 1952 2,582,459 coMPosrrloN Foa oIL WELL CEMENTING Richard A. Salathiel, Houston, Tex., assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N. J., a corporation of Delaware Application November 3, 1948, Serial No. 58,127

6 Claims. (CAI. 10G-90) The present invention is directed to an improved composition for oil Well cementing. More particularly, the invention is directed to a composition comprising a cement slurry suitable for use in cementing wells which remains fluid for a sufficient length of time to enable it to be pumped into subsurface formations.

Prior to the present invention, it has been known to add various components to cement used in cementing wells drilled in the earths formation, particularly in cementing oil wells prior to bringing the wells into production. It has been customary to cement the casing at the desired point and then to penetrate the cement by employing perforating bullets. The conventional cements employed in such service are the slowsetting hydraulic cements which have many undesirable features. In the first place, the cements employed heretofore have4 high mechanical strength and tend to shatter when subjected to mechanical shock. Also, slurries of such cements, if suiciently concentrated to avoid excessive settling, have high viscosities which make it diillcult to place them at the desired point against the subsurface formation. The conventional cements also tend to approach their ultimate strength gradually, which is detrimental in some cases.

It has been known to add bentonitic clays in small amounts to cements to impart to their slurries such characteristics as increased viscosity, increased angle of repose, decreased settling, en hanced mechanical strength, and quickened setting of the cement. It ,has4 alsobeen known t0- add various addition agents such as aromatic s lfgn'c acids :mlm of lgnin sulfonlg agi. to concrete and hydraulic c e o xnase Workabilit or pl sti 't of the cement in the wet sta'te". The mounts of these materials added have been small and the cements to which they have been added have had commercially acceptable compressive strengths. Thus, the prior art teachings have been to the effect to em-l ploy cements consisting of aggregates, bentonitic clays, and dispersing agents such as the salts of the aromatic sulfonic acids and the lignln sulfonic acids in very small amounts in conventional concrete used for building and pouring purposes. The quantities of these materials conventionally used have been such as to leave the strength of the resulting concrete substantially unimpaired.

The cements employed by the prior art, therefore, that include the aforementioned addition agents are largely unsuitable in cementing oil wells, since desirable features of a cement for use in oil wells are absence of aggregates and' low mechanical strength that will prevent shattering under sudden impact such as that resulting from periorating the cement with bullets to bring the oil well into production. Cements used in oil wells should also have the property of being perforated readily.

It is, therefore, the main object of the present invention to provide an improved cement which has a low mechanical strengthard'which will not shatter under high impact.

Another object of the present invention is to provide a slow-settin regiment slurry wichnhas Another object is to provide a cement slurry which will not lose water and bleed after it has reached the formations into which it is introduced.

The o b jects of the present invention may be achieved rwvfdngw*yempsition including cement, a collpidalclay, a sqlublgsaltf a sfu`lf9 x 1ic acid, and water to which may be added suitable additves of the type of carbonates, hex

metaphoswliaes. and hicarbonates.

Briefly then, the invention may be described as involving an improved composition comprising cemmrllwjih, aeelhialglay, a soluble salt 9; a sulfonlc aci such as an aromatic sulfonic acid ofl'wctedy' @E Ilidlllfnnc acid, each in carefully controlled amounts, and wter sufficient to make the necessary slurry to cause the cement to set up properly.

In practicing the present invention, the cement component of the improved composition usually will comprise between 40 and 70% by weight` of the mixture. The cement employed will usually be a high early strength hydraulic cement of the grade supplied on the market. The

colloidal cla Will be employed in an amounu less tl'anj by weight of the dry cement and no m'lr'than about SSfZLby weight. Suitable clays are those such as Wyoming bentonite clays, El Paso surface clay, and those including the montmorillonites and particularly the sodium montmorillonltes. However, the calcium montmorillonites may be employed and suitably other salts of the montmorillonites may be used, but the sodium montmorillonites such as those encountered i111 Wyoming bentonite is the preferred type of c ay.

The salt of the sulfonic acid may be a salt of an aromatic sulfonic acid such as those employed by Tucker in U. S. 2,141,569,01` those disclosed in the patent to Mark, U. S. 2,141,570. These compounds may be termed salts of sulfonic acids having a plurality of aromatic nuclei. The salts of the sulfonic acid, either aromatic or lignin invention, it may be preferred in certain gaSSL .thmllnefnr adding thememeniaebecause mixing the clay ,with t water before the cement and the other in gredients of the composition are added makes 1t possible to use less clay than when the clay is added .'to the water and cement. For example, in some instances as little as one-half as much clay will be required if it is well hydrated before the cement is added. However, for convenience in handling of materials at'the drilling location, it will usually be advantageous to have the cement, clay, and dispersing agent dry-mixed together before bringing them to the well for mixing with water. As a general rule, it may be stated that the water-tc-cement ratio to be used in my improved cement will ordinarily be selected on the basis of the desired strength of the set cement or the density of the cement slurry which is desired within the ranges given.

The invention will .be further illustrated by reference to the following example in which a composition was made up as follows:

Per Cent subsumee Added ze slurry bggll Slurry High Early Strength Portland Cement 50.6 Wyomin Bentonite Clay 6.08 Soluble alcium Lignosullonate 0.15 Sodium Hexametaphosphate 0. 056 Water. 43.3

The solid materials given in the foregoing table were mixed dry and water was then added to make a slurry. 'Ihe slurry was then tested and found to have the following characteristics:

In order to illustrate the invention further, a composition was made up in accordance with the present invention including 10 gallons of water, 04 pounds of high early strength Portland cement to which had been added, on a dry basis, 16% by weight of Wyoming bentonite and 0.5% by weight of soluble calcium lignosulfonate. This composition was tested to determine its iluidity at different rates of shear in the Stormer viscosimeter and was compared with the rates of shear in the Stormer viscosimeter of a 40% (4.5 gallons of water for 94 pounds of cement) slow setting Portland cement slurry. The results of these tests are presented in Fig. 1, which is a graph showing the revolutions per minute on the Stormer viscosimeter plotted against the driving force in grams and illustrates the comparable fluidity of the improved composition of the present invention with conventional cements. It will be seen that the improved cement slurry was more fluid at all rates of shear than was the conventional cement slurry, with the difference being greatest at the lower rates of shear.

The cement slurries made up in accordance with this example were then allowed to set in stoppered test tubes for 24 hours. After this period of setting, the samples were examined and no water was observed above the improved composition after setting, while 3% by volume of .waterhad separated from the conventional cement slurry. These results indicate that the improved slurry had improved characteristics over conventional slurries. It is to be understood that. if higher percentages of water had been employed inthe conventional slurry, a larger amount of water would have been separated.

Another composition in accordance with the present invention was prepared as follows: l0 gallons of water and 94 pounds of high early strength Portland cement containing 16% Wyoming bentonite clay and 0.5% of soluble lignin sulfonate, on the dry basis of the'xftwr' It1matly` admxed. A portion of the resulting cement slurry was then tested by applying a pressure of 50 pounds per square inch to the cement slurry over a lter bed area of 7 square inches. Only about 60 milliliters of filtrate separated from the improved composition of the present invention while under comparable conditions of pressure and time with a conventional slurry of 4.5 gallons of water per 94 pounds of slow setting Portland cement without additives, milliliters of filtrate flowed from the conventional slurry. These data show the improved ltration characteristics of the composition of my invention.

,A cement slurry made up from high early strength Portland cement containing 10 gallons of water per 94 pounds of cement and 14% by weight of bentonite, based on the dry cement, was prepared. One portion of this slurry was tested asprepared and to other separate portions soluble calcium lignosulfonate was added in amounts ranging from 0.1% by weight, on a dry basis, of the cement to 0.9% by weight, making a total of nine different slurries. These nine slurries were then tested in the Halliburton consistometer at a bath temperature of F. The results of these tests are presented in Fig. 2 in which the consistency in poises is plotted against stirring time in hours for the slurries containing varying amounts of the soluble calcium lignosulfonate. It will be seen from an examination of Fig. 2 that the slurry without the soluble calcium lignosulfonate had an initial consistency of 40 poises which increased to about 55 after about 15 minutes of stirring, dropped back to 40 after one-half hour stirring, and from thence rose rapidly after 45 minutes to about 100 poises. The addition of 0.1% by weight of soluble calcium lignosulfonate decreased the A of 40 poises to a After about 45 minutes the consis ncy a risen to about 40 and after 1 hour of stirring to 100 poises. The data further show that amounts ranging from 0.2 to 0.9% of the soluble calcium lignosulfonates reduced the consistency to-an even greater degree, to values in the neighborhood of l0 poises and less. In all cases excepting that of the slurry containing 0.1% by weight of soluble calcium lignoafter one hours stirring and in the case of those slurries containing 0.5% and more of the soluble calcium lignosulfonate, the consistency remained below 20 poises vafter long stirring times in excess of 3 hours. These data show the effect of the concentration of soluble calcium lignosulfonate on the consistency and thickening time of my improved composition.

In order to obtain the effect of temperature and time on the thickening of an improved composition in accordance with my invention, a. composition was made up containing gallons of water per 94 pounds of high early st rgngth Port- 'iijcement to which was added, respectively, 16% and 0.5% of Wyoming bentonite clay and soluble calcium lignosulf'ri' Ey weight of dry cement. "40%slur`5f4.5gllons of water per 94 pounds) of slow setting Portland cement was made up for compatv'poss`i"d"`tests on the two slurries were made on the Halliburton consistometer at bath temperatures of 150 F., 175 F. and 200 F. The results of these tests are shown in Fig. 3. It will become apparent from an examination of Fig. 3, in which the consistency in poises is plotted against time of stirring, that the improved composition remained uid for a considerable length of time, which permits an adequate time for pumping into the subsurface formation, and thereafter set rapidly. It is also apparent from an examination of the data that the viscosity of the conventional slurry was much higher than that of the improved coinpostion throughout the pumpability time; thereafter its rate of setting was much slower than that of my improved composition.

In order to illustrate the strength of the improved composition of the present invention, a composition similar to that described in the preceding example was formed into briquettes and' allowed to set. A composition of the present invention comprised a slurry of 10 gallons of wat/erper 94 pounds of Qgrtland cement to which Tas added 16% Wyoming bentonite and 0.5% by weight of calun lignosulfonat based on the dry cemen`t` 'Ifi'eotliersliiryiis the 40% slurry (4.5 gallons of water per 94 pounds) of slow setting Portland cement. Briquettes were id'p and were" v'testedi'or tensile strength after 1/3, 1/2, 1, 2, 7, and 35 days aging at 175 F. It will be seen from an examination of the data shown in Fig. 4 that the briquettes made up from compositions in accordance with the present invention reached a tensile strength of about 200 pounds per square inch after l day and the tensile strength remained in the neighborhood of 200 pounds until after 7 days age and thereafter fell off slightly to about 185 pounds after 35 days age, whereas the conventional cement slurry reached a tensile strength after 1 days aging of approximately 240 pounds; the tensile strength rose rapidly to 440 pounds after 2 days and thereafter rose to the neighborhood of 540 strength" llortlandlpemewrit and 0.5% bfV soluble" pounds after 7 days and continued to rise to about 575 pounds tensile strength after 35 days aging. It will be apparent that thewilltimate strength of the cementuisnmuch more quickly @V d hnnheuimnioyed composition of the present invention than by the conventional slow setting composition. The data also abundantly demonstrate that the compositions of the present invention have lower ultimate stingjlisrthan those of conventionliisitions, This featurfd'sirable in oil well cements because it allows the bullets employed in perforation to penetrate the cement without shattering it.

A series of four compositions was prepared containing varying amounts of different clays. In each case the clay and soluble calcium lignosulfonate were mixed with the dry cement before adding water. Each composition included 10 gallons of water per 94 pounds of high early calcium lignosulfonate by weight of dry cement. fe psfirbitained 32% by weight, on the dry basis of the cement, of El Paso clalwhile the other compositions contained, respectively, 20%, 16%, and 14% by weight of Wyoming bentonite clay. The four compositions'taning varying amounts of clay were then tested by the Halliburton consistometer at a bath temperature of F. The data obtained are plotted in the attached Fig. 5 in which consistency in poises is plotted against stirring time. These data show the effect of the amount and kind of clay used in the 'compositions of my invention. The Wyoming bentonite clay is preponderately a highly colloidal, sodiummpntmorillonite clay, whereas maso surface clay contains considerably less colloidal material.

In order to illustrate further the desirable characteristics of the composition of the present invention, gun perforating test-setups were prepared by centering NAZ-inch, 15-pound casing inside an 8%inch, 20-gauge sheet metal cylinder, which in turn was centered inside a 55-gallon capacity steel barrel. The entire volume, excluding the inside of the 51/2-inch casing, was lled with cement slurry. Similar set-ups were prepared with different slurries which were mixed as follows: 4.5 gallons of water per 94 pounds of la slow set cement; 6.2 gallons per 94 pounds of high early strength cement; and 10 gallons per 94 pounds of a high early strength cement made up in accordance with the present invention which contained 15% of Wyoming bentonite and 0.5% of calcium lignosulfonate based on weight of dry cement. Duplicate tests of each cement were prepared making a total of six different test-setups. Tensile strength briquettes were poured from the test cement slurries and aged under water at the test site. These cements were then allowed to age in preparation for gun perforation tests. Data on the cement slurries are presented in the following table:

Waterto Tensile Strength- "1 Type w Cln i??? Wd Barre o ement a o e ora No. Gals. Days When In 24 Hrs. Sack 1 Perforated at 175 F.

Lbs/aq: in. Lbalaq. in. I Blow-Set 4. 5 6 416 400 1I-.. do 4.5 6 416 III High Early Strength 6. 2 7 378 360 IV do 6.2 7 378 360 V Improved Composition l0 7 211 176 VI -fln 10 7 211 176 'Ihe gun perforating tests were then made on each of the test-setups when the cement slurries had developed approximately the same strength at atmospheric temperature as they would have developed in 24 hours at 175 F.

A 4-inch gun with a -inch bullet and 105- grain powder charge was employed to perforate barrels I, II, III, and V. It was noted that the bullets had penetrated completely the test-setup of barrels III and V. Barrels IV and VI were then perforated using a 31%-inch gun with a --inch bullet and a 55-grain powder charge. The above series constitutes test A. Barrel I was reperforated using the 31%-inch gun to obtain comparative penetration data. This reperforation is designated test B. The depths of penetration of the bullets into each cement are shown in Figs. 6 and 7, where each bullet has been indicated by number in each test barrel.

It will be seen that the average penetration obtained with the 4-inch gun and 10S-grain powder charge into the slow set cement was 3% inches. Two of the three bullets iired into the high early strength cement penetrated the entire test-setup and struck the boiler plate which had been placed around the barrel. The third was found protruding through the 55gal1on capacity steel barrel. The fourth shot failed to re. On the other hand, all four bullets fired into the cement of the present invention penetrated completely the test-setup and struck the boiler plate with considerable force. With the 31%-inch gun with the 55-grain powder charge. the average penetration into the three cements was as follows:

Inches slow set H High early strength 1% Cement of present invention 41x;

It has been estimated that 31% of the energy from the 4-inch gun, 1i-inch bullet, and 105- grain powder charge, was expended in penetrating the 51/2-inch casing and that 71% of the energy from the 31%-inch gun, i1-inch bullet, 55- grain powder charge was expended in penetrating the 51/2-inch casing. Considering the data obtained with the 31%-inch gun, calculations revealed that 42% of the total energy from this gun was consumed in penetrating one inch of slowset cement, 17.8% of the energy was required to penetrate one inch of the high early strength, and 7.2% of the energy was required to penetrate one inch of the improved cement. Extending these calculations, it may be shown that the 4i nch gun, 1S-inch bullet, 10S-grain powder charge provides sufficient energy to penetrate the 51/2-inch casing and 22 inches of the improved cement.

In determining the penetration of the bullet, evidence of compaction along the path of the bullet and directly ahead of the bullet was noted in both the slow-set and high early strength cement; no such evidence of compaction was observed in the improved cement. On examining the diierent types of cement, some cracking was observed in both the slow set and high early strength cements, but very little, if any, cracking was evident in my improved cement.

The sizes of the holes made by the bullets in the three cements tested were then compared. It was noted that the size of the hole increased as the strength of the cement decreased which is highly desirable. With the 4-inch 'gun with a 10S-grain powder charge, the holes in the high 75 in which the salt of lignin sulfonic acid is a calneunte,

early strength cement were about V4 inch in diameter, while the holes in the improved cement composition were nearly 1 inch in diameter. In all three cements, however, holes of approxis mately bullet size were obtained using the 311;-

inoh gun with a 55-grain powder charge. It was observed that the holes were larger than bullet size when the bullets penetrated completely the test-setup whereas when the bullets lodged within l the test-setup, the holes were nearly bullet size.

It will be seen from the foregoing results that greater penetrations may be obtained by penetrating casings cemented with the improved cement than with conventional cements. It will l also be noted that cements having approximately D-pound tensile strength in accordance with my invention allow greater penetration than cements having greater tensile strength.

It is to be reiterated that the compositions in 20 accordance with my invention are based on the contributing effects of the various ingredients of my compositions. Thus, the callgiggglay, the salt 9f,1i.1 .$.ulonic.acid, such as aromatic and yare to the effect thatv the dispersing agents employed in my improved compositions had little or no effect on the compressive strength of the cement and that the bentonite clay, when the water-to-cement ratio was held constant, in-

:15 creased mechanical strength rather than reduced it. My invention, therefore, is directed to a composition including cement, colloidal clay in a carefully controlled amount, and a water soluble salt of sulfonic acid, such as an aromatic sul- 4o fonic acid and lignin sulfonic acid in a carefully controlled amount, and water which may contain other additives such'as sodiinqrbihexarnetaphos; hate segiemaaraqiata Sodiuglxmxide. and

Lr-m ammatgw Only ifthefirst four ingreien s are present are the improved results obtained. While it may sometimes be desirable to use the sodium carbonate, sodium bicarbonate,

sodium hexametaphosphate, and siihydrcxl ide, the use of these materials may be optional;

however, the other ingredients are necessary.

The nature and objects of the present invention having been completely described and illusand to secure by Letters Patent is:

\trated, what I wish to claim as new and useful 1. An improved composition suitable for use in cementing wells which consists of a Portland cement, an amount of a watersolu b lg sa lt o gnm i i :gal-m 0.1 and 1.0%

ry cement, a colloidal clay 1n a by weigh of "0 amount in the range between 5% and 35% by weight of dry cement and water in an amount suflicient to provide a pumpable slurry.

2. A composition in accordance with claim 1 in which the colloidal clay is a bentonitic clay.

3. An improved composition suitable for use in cementing wells which consists of an amount of Portland cement in the range between 40 andA by weight, a colloidal clay in an amount in the range between 5% and 35% by weight of dry 70 cement, a water soluble salt of lignin sulfonic acid in an amount in the range between 0.1 and 1.0% by weight of dry cement, and the remainder water.

4. A composition in accordance with claim 3 9 cium salt and the colloidal clay is a, bentonitic clay.

5. An improved composition suitable for use in cementing wells which consists of Portland cement, about 16% by weight of colloidal clay, 0.5% by weight of calcium lgnin sulfonate, both based on the dry cement, and approximately 10 gallons of Water for each 94 lbs. of cement.

6. A composition in accordance with claim 5 in which the colloidal clay is bentonite.

RICHARD A. SALATHIEL.

lll

l0 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. AN IMPROVED COMPOSITION SUITABLE FOR USE IN CEMENTING WELLS WHICH CONSISTS OF A PORTLAND CEMENT, AN AMOUNT OF A WATER-SOLUBLE SALT OF LIGNIN SULFONIC ACID IN THE RANGE BETWEEN 0.1 AND 1.0% BY WEIGHT OF DRY CEMENT, A COLLOIDAL CLAY IN AN AMOUNT IN THE RANGE BETWEEN 5% AND 35% BY WEIGHT OF DRY CEMENT AND WATER IN AN AMOUNT SUFFICIENT TO PROVIDE A PUMPABLE SLURRY. 